Tlin GROWTH or GENES 



physiologically analogous with a plasniagene and therefore represents 

 a relapse to the kind of organization that must have preceded the 

 invention of sexual reproduction. 



The second limit to the growth of the super-gene is that which 

 is reached by the suppression of sexual reproduction in any apomictic 

 species of higher organism. Where meiosis and fertilization fail, 

 as they do in triploid species of beetles and dandelions, heredity 

 may vary, as we saw, by the occasional loss or gain of chromosomes; 

 but the mitotic nucleus is the working unit of heredity. Recom- 

 bination has been abandoned. The new type, unlike the heterocaryon, 

 can no longer adapt itself to changing conditions, hi attaining its 

 maximum size of super-gene, the whole nuclear outfit, evolution 

 has run its course. 



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